Have a couple I want to air today.

First was at my first gig as a dev, 4-5 months out of school. I was the only dev at a startup where the owner was a computer illiterate psycopath with serious temper tantrums. We're talking slamming doors, shouting at you while you are on the phone with customers, the works...

Anyways, what happened was that we needed to do an update in our database to correct some data on a few order lines regarding a specific product. Guess who forgot the fucking where-clause... Did I mention this boss was a cheap ass, dollar stupid, penny wise asshole that refused to have anything but the cheapest hosting? No backups, no test/dev/staging environment, no local copies... Yeah, live devving in prod, fucking all customers with a missing semi-colon (or where clause).

Amazingly, his sheer incompetance saved my ass, because even if I explained it, he didn't get it, and just wanted it fixed as best we could.

The second time was at a different company where we were delivering managed network services for a few municipalities. I was working netops at that time, mostly Cisco branded stuff, from Voice-over-IP and wifi to switches and some routing.

One day I was rolling out a new wireless network, and had to add the VLAN to the core switch on the correct port. VLAN's, for those who don't know, are virtual networks you can use to run several separated networks on the same cable.

To add a VLAN on a Cisco switch one uses the command:

switchport access vlan add XYZ

My mistake was omitting the 'add', which Cisco switches happily accept without warning. That command however can be quite disruptive as it replaces all of the excisting VLAN's with the new one.

Not a big deal on a distribution switch supplying an office floor or something, but on a fucking core switch in the datacenter this meant 20K user had no internet, no access to the applications in the DS, no access to Active Directory etc. Oh and my remote access to that switch also went down the drain...

Luckily a colleague of mine was on site with a console cable and access to config backups. Shit was over within 15 minutes. My boss at that time was thankfully a pragmatic guy who just responded "Well, at least you won't make that mistake again" when we debriefed him after the dust settled.